help required please!

[chrishesketh]

I'm not sure where to put this, but I'm guessing it's electrical... when I brake my revs drop to 0 but if I release the brake they go back up, in an out of gear this happens!

whilst stationary outside my house, I disconnected the wires to the brake pedal and tried again whilst in neutral, nothing happened! plugged back in revs dropped and stalled! unplugged to double check nothing, plugged back in stalled!!

any ideas whats wrong???

thanks in advance

 

[Sunglasses_Ron]

How old is your battery?

 

[chrishesketh]

not sure ron, will check tomorrow how many volts it's got when I wake up!

 

[chrishesketh]

How old is your battery?

will check in the morning [emoji106]

 

[Sunglasses_Ron]

I'm far from being an expert but I think that's where I'd be looking first

 

[MicKPM]

Do you mean the car actually stalls or do you mean the tacho needle just drops to 0?

 

[chrishesketh]

Do you mean the car actually stalls or do you mean the tacho needle just drops to 0?

the revs will drop to 0 causing it to stall! as soon as I press my brake the revs drop right the way down so say it's at 4k rpm they will drop straight to 0 unless I take my foot off again and they will raise back to normal

 

[chrishesketh]

I'm far from being an expert but I think that's where I'd be looking first

12.89 volts! I'm not expert neither but when I disconnect the wires from the brake pedal the problem goes away? so it's something to do with the wiring or something surely?

 

[MicKPM]

Yep, it'll be the ECU getting a signal to make it cut power... It sounds like it thinks your moving.

Needs the wiring checking

 

[chrishesketh]

Yep, it'll be the ECU getting a signal to make it cut power... It sounds like it thinks your moving.

Needs the wiring checking

cheers mate appreciate the advice, what would be best? an auto electrican or something?

 

[chrishesketh]

what about a vacuum leak?

 

[MicKPM]

A Vac leak would cause engine speed to rise not fall. This is, I am certain, is the ECU getting the command from the brake pedal switch to cut C/C. I've seen it a few times but its normally on the 172 Cup. Usually a short to + somewhere in the loom causing the 5v ref voltage to be constantly applied to the pin.

You need to check the brake light circuit i'm afraid

 

[chrishesketh]

thanks a lot mate really appreciate your help!!! [emoji106]